The rise of AI computing is driving optical interconnects toward higher bandwidth, greater density, and lower power consumption, accelerating the development of CPO and NPO architectures. At CIOE 2026, major optical-fiber manufacturers introduced dedicated polarization-maintaining fiber (PMF) solutions for these emerging applications, highlighting the growing importance of precise polarization control in next-generation optical engines. This article explores how PMF works, how it differs from conventional single-mode fiber, and why a technology that has existed for decades is becoming increasingly relevant to silicon photonics, CPO/NPO, and high-speed AI optical interconnects.